The presence of chemicals within tires, which are capable of migrating, is well known. New tire sidewalls are often coated by the manufacturer with water removable protective paints or coatings, particularly when the tire sidewalls include a non-black component (e.g. a white sidewall) which can be detrimentally stained if the non-black component (whitewall) contacts the typical black colored remainder of another tire for an extended time during shipping or storage of new tires.
Pneumatic tires are generally assembled from a multitude of plies, layers, cords, etc. The components are carefully assembled and adhered to each other on a tire assembly machine. The green tire after removal from the tire assembly machine is vulcanized in a tire curing press. The cured tire from the tire curing press is evaluated for dimensional variations, weight variations, variations from inflating the tire, and variations detectable as the tire is rotated. Tire manufacturers measure and mark these detectable variations as part of their quality control programs. The tire manufacturers use the data from these evaluations to perform in process adjustments to their equipment and process to minimize total variations in subsequent production.
Automobile manufacturers recognized that the tire manufacturer's marking of the location and extent of minor variations between tires could be used to compensatingly match the variations in the tire with variations in other automobile components such as the tire rim. They requested the markings be left on the tires to be shipped to them. Automobile manufacturers requested the markings be made fluorescent because such markings could be mechanically read by machines capable of detecting fluorescent labels or markings and this would facilitate match mounting by machines, such as those machines installing tires on rims.
Most fluorescent labels for this application comprise a release backing, a pressure sensitive adhesive to hold the label on a substrate, an inexpensive face sheet, the top of which is coated with a fluorescent ink. Many of the fluorescent inks are solvent based systems that either require expensive solvent recovery or incineration systems or release solvent into the environment. Automobile manufacturers have experienced problems of poor adhesion of labels to tires and labels which lose their fluorescence during storage on the tires. Generally but not always, the fluorescent labels or markings are removed after match mounting and prior to delivery of the finished automobile to the user.
The term harmonics relates to a variety of sinusoidal components that make up a musical tone. If the first frequency of a tone is 440 Hz then the second will generally be at 880 Hz and the third at 1320 Hz. A measurement of a pneumatic tire as it rotates one revolution can often be a sinusoid. If the measurement produces one minimum value and one maximum value per rotation it will have sinusoidal characteristics with a frequency of 1. Thus, a marking of the first harmonic of a rotating tire usually indicates a minimum or maximum measured value on a sector of a tire for a particular test. A preferred first harmonic test marking is the diameter of the tire.
It would be desirable to have a fluorescent label that retained its initial fluorescent value for many months even while in contact with a black tire sidewall. It would be desirable to manufacture these labels while minimizing the release of harmful organic solvents into the environment.